""Stalin made very tough orders concerning the treatment of German civilians"
The BIG LIE is often more effective than a small one. This sounds like DPRK propaganda.
Stalin's real "tough orders": "Can't he understand it if a soldier who has crossed thousands of kilometres through blood and fire and death has fun with a woman or takes some trifle?"
While there are authentic records detailing Stalin's orders to leave German civilians unmolested, there is also evidence that in many cases the orders were ignored by individual soldiers. Commanding officers on the field often simply "looked the other way". It is doubtful that Stalin himself expected his orders to be obeyed or seen as anything more than a formality. Certainly the kind of violence perpetrated by advancing Russian soldiers would be consistent with Stalin's own well-known violent history.
I actually visited St Petersburg in the summer of 2000, and there is still-- after 50 years-- alot of tangible anger at Germany and Nazism. Eastward advancing Nazis lined up men women and children indiscriminately. The horros inflicted on the Russian people are well documented (it was actually especailly bad in Ukraine).
While this doesn't excuse the Soviet atrocites to follow, it's important to look at the events in context. There was justifiable anger on the part of Russian soldiers-- which was then amplified by Soviet propaganda-- leading to often brutal acts of retaliation against German civilians.